ML2 bigswitch driver modifies PortContext.current

[Robert Kukura]

The ML2 bigswitch mechanism driver's create_port_postcommit() and update_port_postcommit() methods pass the PortContext to a _prepare_port_for_controller() method that modifies the port dictionary accessed as PortContext.current. This modified port dictionary is currently returned by ML2 as the result of the port create or update operation, but the changes do not get persisted in the DB. The fix for bug 1276391 is likely to result in these changes no longer being returned to the client. Mechanism drivers are not supposed to modify this port dictionary, except by calling PortContext.set_binding() from within bind_port(). It does not appear that this mechanism driver actually binds ports. If the port dictionary needs to be modified before being passed to the bigswitch controller, it should be copied first.

Also, the TestBigSwitchMechDriverPortsV2.test_port_vif_details() unit test asserts that the returned binding:vif_type is the modified value, so this test will also need to be changed or eliminated as part of this fix.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/81360

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/81360
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=9014f66fce619af6d72823b3fdb0ecf148582649
Submitter: Jenkins
Branch: master

commit 9014f66fce619af6d72823b3fdb0ecf148582649
Author: Kevin Benton <email address hidden>
Date: Tue Mar 18 12:11:53 2014 -0700

    ML2 BigSwitch: Don't modify parent context

    Makes a copy of the port context before changing
    it in preparation for the backend controller so
    other drivers are not affected. Also removes a
    UT that was exercising direct modification of VIF
    details in the port context, which is not allowed
    by the ML2 plugin.

    Closes-Bug: #1294308
    Change-Id: I47281dcd23c022813b8b6eda0a3d39c4482277b9